QIWI CTF 2016 - Crypto 300_1

Crypto 300_1

Crypto - 300 Points

Alice, Bob, and Cameron want to get shared key by Diffie-Hellman method. Their public keys respectively are g^a mod p, g^b mod p, g^c mod p. Will Alice and Bob be able to get shared key without Cameron’s private key? The flag is the first 20 digits of the shared key in decimal form.